Rabbet

The line being cut to the left, nearest the bottom of the keel, is the rabbet line. The middle depth- the apex. The right most and upper line- the bearding line. note the wider spacing between the apex and bearding lines to accommodate the planking as it makes a steeper entry into the keel near the stern.

This week we’ve been cutting out the rabbet or rebate as it is sometimes spelled on our keel and stem assembly. A rabbet is a 90 degree inlaid notch cut into the face or along the edge of a piece of wood. The keel and stem have a long rabbet cut into them to accommodate the vessel’s planking. We find the rabbets design from expanding sections of the hull in the lofting. Three points are found which are then battened off to create curved lines which will be connected and chiseled out. The first set of points represents the inside corner or the plank in the rabbet, this is called the “apex” or “inner rabbet”. The second is the “bearding line” which on the keel is the upper line above the apex which is where the face of the garboard or lowermost plank exits its place of contact with the keel. The third and last set of points is the rabbet proper, or the “outer rabbet” as it is sometimes called, which touches the opposing corner of the edge of the plank to that of the apex. These three points are connected to create a 90 degree angle in all cases, however this angle shifts in its orientation to the material depending on whether the planking makes a steeper or more acute approach to the keel such as in the stern or a wider angle such as in the stem. At the bow the planks approach the stem at a very wide angle, we call this characteristic in ship design a “bluff bow”. This means that the distance between the bearding line and apex line gets much wider as we move aft and smaller as we move forward. The depth of the rabbet in relation to the face of the material changes as well. The planking which will land in our rabbet is 2 1/4” ,however because of its changing approach to the keel and stem it is much deeper in the stern and shallower at the bow. Because of the complexity of this shape we have little use of power tools aside for setting the depth and establishing the apex using a skilsaw. We then connect the lines making small 3 inch wide rabbet notches at a couple frame spacings of width apart with chisels. After the notches are made we connect them by quickly wasting material away between the established notches. We then work material down to an acceptable surface with an accurate 90 degree angle to power plane with the power rabbet planer. It might also be noted that in some building styles particularly that of wooden work boat construction in the Chesapeake Bay, the rabbet is eliminated by building using and inner stem and keelson which takes a rolling bevel. The inside corner where inner and outer stem meet would create the apex and the outside after edge of the outer stem the rabbet line. The bearding line would be found on the inner stem. We find this method of building at CBMM on nearly all of our deadrise style workboats including our skipjack and buy boat. In some building traditions the inner stem is called the stemliner vs the outer stem simply being the stem proper.

The rabbet in the stem, note the wider spacing between apex and rabbet lines in this portion of the rabbet.